error: missing documentation for macro
  --> $DIR/deny-missing-docs-macro.rs:16:1
   |
LL | macro_rules! foo { //~ ERROR
   | ^^^^^^^^^^^^^^^^
   |
note: lint level defined here
  --> $DIR/deny-missing-docs-macro.rs:13:9
   |
LL | #![deny(missing_docs)]
   |         ^^^^^^^^^^^^

error: Compilation failed, aborting rustdoc